Hydrophobic coating including DLC on substrate

ABSTRACT

A substrate is coated with a hydrophobic coating system including highly tetrahedral amorphous carbon that is a form of diamond-like carbon (DLC). In certain embodiments, the coating system is deposited on the substrate in a manner to increase its hydrophobicity. In certain embodiments, the coating system is deposited in a manner such that it has an average hardness of at least about 10 GPa, more preferably from about 20-80 GPa. In certain embodiments, the coating system includes first and second DLC inclusive layers that are deposited using one or more ion beam deposition devices, wherein different gases are used to deposit the respective DLC inclusive layers such that the overlying layer has greater scratch resistance characteristics than the underlying layer which functions as an anchoring layer.

This is a continuation-in-part (CIP) of U.S. patent application Ser. No.09/303,548, filed May 3, 1999, now 6,261,693, and a continuation-in-part(CIP) of U.S. patent application Ser. No. 09/442,805, filed Nov. 18,1999 now abandoned, the disclosures of which are both herebyincorporated herein by reference.

This invention relates to a hydrophobic coating system includingdiamond-like carbon (DLC) provided on (directly or indirectly) asubstrate of glass, plastic, ceramic, or the like, and a method ofmaking the same. The coating system may include one or more layers andmay be deposited on the substrate utilizing plasma ion beam depositionin certain embodiments.

BACKGROUND OF THE INVENTION

Conventional soda inclusive glasses are susceptible to environmentalcorrosion which occurs when, e.g., sodium (Na) diffuses from or leavesthe glass interior, as well as to retaining water on their surfaces inmany different environments, including when used as automotive windows(e.g. backlites, side windows, and/or windshields). When water isretained or collects on automotive windows, the water may freeze (i.e.forming ice) in certain environments. Additionally, the more waterretained on a windshield, the higher power wiper motor(s) and/or wiperblade(s) required.

In view of the above, it is apparent that there exists a need in the artfor (i) a coated article (e.g. coated glass, ceramic or plasticsubstrate) that can repel water and/or dirt, and a method of making thesame, (ii) a coated soda inclusive glass where the coating(s) reducesthe likelihood of visible stains/corrosion forming; and/or (iii) aprotective hydrophobic coating system that is somewhat resistant toscratching, damage, or the like.

It is known to provide diamond like carbon (DLC) coatings on glass. U.S.Pat. No. 5,637,353, for example, states that DLC may be applied onglass. Unfortunately, the DLC of the '353 patent would not be anefficient hydrophobic coating and/or would not be an efficient corrosionminimizer on glass in many instances.

U.S. Pat. No. 5,900,342 to Visser et al. discloses a fluorinated DLClayer on an electrophotographic element. From about 25-65% fluorinecontent by atomic percentage is provided at an outermost surface, toprovide for low surface energy in an attempt to make removal ofxerographic toner easier. Unfortunately, this DLC inclusive layer of the'342 patent would be too soft for use on a glass substrate in automotiveapplications and the like. Its apparent lack of sp³ C—C bonds and/orlack of Si—O bonds contribute to its softness. It is also believed thatcontinuous exposure to sun, rain, humidity, dust, windshield wipers,and/or the environment in general would cause the '342 DLC layer tobreak down or degrade rather quickly over time.

Thus, there also exists a need in the art for a DLC inclusive coatingthat has sufficient hardness and durability to withstand the environmentwhile still exhibiting satisfactory hydrophobic qualities.

It is a purpose of different embodiments of this invention to fulfillany or all of the above described needs in the art, and/or other needswhich will become apparent to the skilled artisan once given thefollowing disclosure.

SUMMARY OF THE INVENTION

An object of this invention is to provide a durable coated article thatcan shed or repel water (e.g. automotive windshield, automotivebacklite, automotive side window, architectural window, bathroom showerglass, residential window, bathroom shower door, coated ceramicarticle/tile, etc.).

Another object of this invention is to provide a hydrophobic coatingsystem including one or more diamond-like carbon (DLC) inclusive layers.

Yet another object of this invention, in embodiments where a hydrophobiccoating system includes multiple DLC inclusive layers, is to form (e.g.,via ion beam deposition techniques) a first underlying DLC inclusivelayer using a first precursor or feedstock gas and a second DLCinclusive layer over the first underlying DLC inclusive layer using asecond precursor or feedstock gas. In certain embodiments, the firstunderlying DLC inclusive layer may function as an anchoring and/orbarrier layer while the second or overlying DLC inclusive layer may bemore scratch resistant (i.e., harder) and more dense so as to improvethe coated article's durability and/or scratch resistancecharacteristics.

Another object of this invention is to provide a DLC inclusive coatingsystem including (i) an underlying DLC inclusive layer formed using aprecursor/feedstock gas such as tetramethylsilane (TMS), and (ii)another DLC inclusive layer formed over the underlying layer (i) usinganother precursor/feedstock gas such as acetylene (C₂H₂), in a mannersuch that layer (i) functions as a barrier and/or anchoring layer andthe overlying layer (ii) is of a more durable (e.g., scratch resistanceand/or hard) nature. In such embodiments, the underlying DLC inclusivelayer (i) may include silicon (Si) so as to provide improved bonding ofthe overlying layer (ii) to the substrate. The overlying layer may ormay not include silicon (Si) in different embodiments.

Another object of this invention is to provide a coated substrate,wherein a coating system includes sp³ carbon-carbon bonds and has awettability W with regard to water of less than or equal to about 23mN/m, more preferably less than or equal to about 21 mN/m, even morepreferably less than or equal to about 20 mN/m, and in most preferredembodiments less than or equal to about 19 mN/meter. This can also beexplained or measured in Joules per unit area (mJ/m²)

Another object of this invention is to provide a coated substrate,wherein a DLC inclusive coating system includes sp³ carbon-carbon bondsand has a surface energy γ_(C) (on the surface of the coated article) ofless than or equal to about 20.2 mN/m, more preferably less than orequal to about 19.5 mN/m, and most preferably less than or equal toabout 18 mN/m.

Another object of this invention is to provide a coated substrate,wherein a DLC inclusive coating system has an initial (i.e. prior tobeing exposed to environmental tests, rubbing tests, acid tests, UVtests, or the like) water contact angle θ of at least about 80 degrees,more preferably of at least about 100 degrees, even more preferably ofat least about 110 degrees, and most preferably of at least about 125degrees.

Another object of this invention is to provide a coating system for aglass substrate, wherein the coating system includes a greater number ofsp³ carbon-carbon (C—C) bonds than sp² carbon-carbon (C—C) bonds. Incertain of these embodiments, the coating system need not include manysp² carbon-carbon (C—C) bonds.

Another object of this invention is to provide a coated glass articlewherein a DLC inclusive coating system protects the glass from acidssuch as HF, nitric, and sodium hydroxide (the coating may besubstantially chemically inert).

Another object of this invention is to provide a coated glass articlethat is abrasion resistant.

Another object of this invention is to provide a DLC coating system on asubstrate, wherein the coating includes different portions or layerswith different densities and different sp³ carbon-carbon bondpercentages. The ratio of sp³ to sp² carbon-carbon bonds may bedifferent in different layers or portions of the coating. Such a coatingsystem with varying compositions at different portions thereof may becontinuously formed (e.g., by varying feedstock and/or precursor gas(es)used, and/or by varying the ion energy used in the deposition process,using a single ion beam deposition device). Thus, a DLC inclusivecoating system may have therein an interfacial layer with a givendensity and chemical makeup, and another outer or overlying layerportion having a higher density of sp³ carbon-carbon (C—C) bonds andgreater scratch resistance and/or durability.

Another object of this invention is to manufacture a coating systemhaving hydrophobic qualities wherein the temperature of an underlyingglass substrate may be less than about 200° C., preferably less thanabout 150° C., most preferably less than about 80° C., during thedeposition of a DLC inclusive coating system. This reducesgraphitization during the deposition process, as well as reducesdetempering and/or damage to low-E and/or IR-reflective coatings alreadyon the substrate in certain embodiments.

Yet another object of this invention is to fulfill any and/or all of theaforesaid objects and/or needs.

In certain embodiments, this invention fulfills any and/or all of theabove listed objects and/or needs by providing a coated articlecomprising:

a substrate;

a coating system including first and second diamond-like carbon (DLC)inclusive layers provided on said substrate, said first layer furtherincluding silicon (Si); and

wherein said coating system has an initial contact angle θ with a dropof water of at least about 80 degrees, and an average hardness of atleast about 10 GPa.

In other embodiments, this invention fulfills any and/or all of theabove-listed needs and/or objects by providing a method of making acoated article, the method comprising the steps of:

providing a substrate;

depositing a first DLC inclusive layer on the substrate using a firstgas including silicon (Si); and

depositing a second DLC inclusive layer on the substrate and on thefirst DLC inclusive layer using a second gas different than the firstgas in a manner such that the resulting article has an initial contactangle θ of at least about 80 degrees.

In yet other embodiments, this invention fulfills any and/or all of theabove listed objects and/or needs by providing a method of making acoated article, comprising the steps of:

providing a substrate;

depositing a first diamond-like carbon inclusive layer on the substrateby using at least one of the following gases in an ion beam depositionapparatus: a silane compound, an organosilane compound, anorganosilazane compound, and an organo-oxysilicon compound; and

depositing a second diamond-like carbon inclusive layer directly on andover the first diamond-like carbon inclusive layer by using ahydrocarbon gas in an ion beam deposition apparatus. The same ordifferent ion beam deposition apparatus(es) may be used in the differentsteps. In certain embodiments, the second diamond-like carbon inclusivelayer may have greater hardness and greater density than the underlyingfirst diamond-like carbon inclusive layer, to make the coating systemmore durable.

In still other embodiments, this invention fulfills any and/or all ofthe above listed needs and/or objects by providing a coated articlecomprising:

a substrate;

a coating system including at least one diamond-like carbon (DLC)inclusive layer provided on said substrate; and

wherein said coating system has an initial contact angle θ with a dropof water of at least about 80 degrees, an initial tilt angle β of nogreater than about 30 degrees, and an average hardness of at least about10 GPa.

This invention will now be described with respect to certain embodimentsthereof, along with reference to the accompanying illustrations.

IN THE DRAWINGS

FIG. 1 is a side cross sectional view of a coated article according toan embodiment of this invention, wherein a substrate is provided with aDLC inclusive coating thereon having hydrophobic qualities and multiplelayers or layer portions.

FIG. 2 is a side cross sectional view of a coated article according toanother embodiment of this invention, wherein the DLC inclusive coatingor coating system of FIG. 1 is provided over an intermediate layer(s).

FIG. 3 is a side cross sectional partially schematic view illustrating alow contact angle θ of a drop on a glass substrate.

FIG. 4 is a side cross sectional partially schematic view illustratingthe coated article of the FIG. 1 or FIG. 2 embodiment of this inventionand the contact angle θ of a water drop thereon.

FIG. 5 is a perspective view of a linear ion beam source which may beused in any embodiment of this invention for depositing a DLC inclusivecoating system including one or more DLC inclusive layer(s).

FIG. 6 is a cross sectional view of the linear ion beam source of FIG.5.

FIG. 7 is a diagram illustrating tilt angle as discussed herein inaccordance with certain embodiments of this invention.

FIG. 8 is a chart illustrating the atomic amounts of carbon, oxygen, andsilicon (relative only to one another) at different thicknesses of asample coating system in accordance with the FIG. 1 embodiment of thisinvention.

FIG. 9 is a thickness vs. atomic concentration graph illustrating thedifferent amounts of the materials of FIG. 8 as a function of depth intothe coating system of the FIG. 8 coating system.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like elements throughout theaccompanying views.

FIG. 1 is a side cross sectional view of a coated article according toan embodiment of this invention, wherein a diamond-like carbon (DLC)inclusive coating system 5 including at least two layer 2, 3 is providedon substrate 1. Substrate 1 may be of glass, plastic, ceramic, or thelike. In preferred embodiments, each of the layer 2 and 3 of the coatingsystem 5 in the FIG. 1 embodiment includes at least some amount ofhighly tetrahedral amorphous carbon (ta-C). Highly tetrahedral amorphouscarbon (ta-C) forms sp³ carbon-carbon bonds, and is a special form ofdiamond-like carbon (DLC). Coating system 5 functions in a hydrophobicmanner (i.e., it is characterized by high water contact angles θ and/orlow surface energies as described below), and optionally may becharacterized by low tilt angle(s) β in certain embodiments.

According to certain embodiments of this invention, while layer 2 and 3each include DLC, the two layers are deposited using different precursoror feedstock gases so that the two layers have differentcharacteristics. In an exemplary embodiment, underlying or anchor DLCinclusive layer 2 is deposited using an ion beam deposition techniqueutilizing a TMS (tetramethylsilane) inclusive precursor or feedstockgas; while overlying DLC inclusive layer 3 is deposited using an ionbeam deposition technique utilizing a C₂H₂ (acetylene) inclusiveprecursor or feedstock gas. It is believed that the underlying layer 2(a silicon doped DLC alloy) deposited using TMS functions as a barrierlayer to prevent certain impurities from getting into or out of thesubstrate. Moreover, when TMS is used in the deposition process ofunderlying anchor layer 2, the Si (silicon) in layer 2 helps to enableoverlying layer 3 to better bond and/or adhere to the glass via anchorlayer 2.

Surprisingly, it has also been found that the use of anchor layer 2(e.g., deposited via TMS gas) provides a more continuous/contiguouscoating on a glass surface at very thin thicknesses as compared to a DLCinclusive layer deposited using C₂H₂ (acetylene) gas directly on glass.As a result, anchor layer 2 can be deposited first directly on the glassat a relatively thin thickness, and the overlying layer 3 need not be asthick as would otherwise be required. In general, the thinner layer 3,the higher the transmission of the overall coating system. Moreover, theprovision of anchor layer 2 may enable improved yields to be achievable,as the occurrence of pinholes in the coating system is less likely.

In such embodiments where DLC inclusive layer 3 is formed on thesubstrate using a C₂H₂ (acetylene) inclusive precursor or feedstock gasand underlying DLC inclusive layer 2 is formed on the substrate using atleast a TMS (tetramethylsilane) inclusive precursor or feedstock gas,the layer 2 and 3 tend to intermix with one another during thedeposition process. Thus, there may not be a clear line delineating orseparating the two layer 2 and 3 in the final product, due to thisintermixing (i.e., ion mixing) of the material from the two layers.However, for purposes of simplicity, the two layer 2 and 3 are referredto and illustrated herein as separate layers due to the differentdeposition processes (e.g., gases and/or energies) used in theirrespective depositions.

It has been found that the outer DLC inclusive layer 3 formed using ahydrocarbon gas, such as C₂H₂ (acetylene), inclusive precursor orfeedstock tends to have a greater hardness and density than doesunderlying DLC inclusive layer 2 formed using a TMS (tetramethylsilane)inclusive precursor or feedstock gas. For example, in certain exemplaryembodiments of this invention, overlying layer 3 may have an averagehardness (measured via a nano-indentation hardness measuring technique)of from about 45-85 GPa, more preferably from about 50-70 GPa, and mostpreferably from about 55-60 GPa. Meanwhile, underlying DLC inclusivelayer 2 may have an average hardness of from about 10-35 GPa, and morepreferably from about 15-30 GPa. Thus, the overlying layer is harderthan the underlying layer, so as to make the end product more scratchand/or abrasion resistant. Using the aforesaid nano-indentation hardnessmeasuring technique, the final coating system 5 including both layer 2and 3 may have a hardness of from about 25-60 GPa, more preferably fromabout 30-45 GPa, which is at a hardness value between the respectivehardnesses of the two DLC inclusive layer 2 and 3.

Thus, coating system 5 includes silicon (Si) and DLC inclusive layer 2which functions to improve the bonding characteristics of overlying andharder DLC inclusive layer 3 to the substrate. While the Si in layer 2improves the bonding of layer 3 to substrate 1, it is preferred thatless Si be provided in overlying layer 3 than in layer 2 because theprovision of Si in a DLC inclusive layer may result in decreased scratchresistance and/or decreased hardness. Layer may or may not include Si indifferent embodiments of this invention. While layer 2 allows forimproved bonding to the substrate, the provision of DLC and some sp³carbon-carbon bonds therein allows this anchor layer 2 to have ratherhigh hardness values as discussed above so as to render the resultingproduct more durable and thus resistant to scratching, abrasions, andthe like.

In embodiments where substrate 1 is of or includes glass (e.g.,soda-lime-silica glass), anchor or intermediate DLC inclusive layer 2may be from about 10 to 250 angstroms (A) thick, more preferably fromabout 10 to 150 angstroms thick, and most preferably about 50 angstromsthick; while outer DLC inclusive layer 3 may be from about 10 to 250angstroms thick, more preferably from about 10 to 150 angstroms thick,and most preferably about 60-90 angstroms (Å) thick. However, thesethicknesses are not limiting and the layers may be of other appropriatethicknesses in certain embodiments of this invention. Moreover, inembodiments where substrate 1 is of or includes plastic, layer 2, 3 maybe of greater thickness(es) than those described above.

In certain embodiments, layer 3 may have an approximately uniformdistribution of sp³ carbon-carbon bonds throughout a large portion ofits thickness, so that much of the layer has approximately the samedensity. In such embodiments, layer 2 may include a lesser percentage ofsp³ carbon-carbon bonds near the interface with substrate 1, with thepercentage or ratio of sp³ carbon-carbon bonds increasing throughout thethickness of the coating system 5 toward the outermost surface. Inoverlying DLC inclusive layer 3, at least about 40% (more preferably atleast about 60%, and most preferably at least about 80%) of thecarbon-carbon bonds in layer 3 are of the sp³ carbon-carbon type.

It is believed that the presence of sp³ carbon-carbon bonds in layer 3increases the density and hardness of the coating system, therebyenabling it to satisfactorily function in automotive environments. Layer3 may or may not include sp³ carbon-carbon bonds in differentembodiments, although formation of sp² carbon-carbon bonds is likely inboth layer 2 and 3.

In order to improve the hydrophobic nature of coating system 5, atoms inaddition to carbon (C) may be provided in at least overlying layer 3 indifferent amounts in different embodiments. For example, in certainembodiments of this invention layer 3 (taking the entire layerthickness, or only a thin 10 A thick layer portion thereof intoconsideration) may include in addition to the carbon atoms of the sp³carbon-carbon bonds, by atomic percentage, from about 0-20% Si (morepreferably from about 0-10%), from about 0-20% oxygen (O) (morepreferably from about 0-15%), and from about 5-60% hydrogen (H) (morepreferably from about 5-35% H. Optionally, layer 3 may include and fromabout 0-10% (atomic percentage) fluorine (F) (more preferably from about0-5% F) in order to further enhance hydrophobic characteristics of thecoating. In general, the provision of H in layer 3 reduces the number ofpolar bonds at the coating's surface, thereby improving the coatingsystem's hydrophobic properties by reducing the polar component of thesurface energy.

In certain embodiments, the outermost layer portion (e.g., 5-15 angstromthick outermost or exterior layer portion) of layer 3 may includeadditional H and/or F atoms for the purpose of increasing the coatingsystem's hydrophobic qualities. In such embodiments, the deposition ofadditional H atoms near layer 3's surface results in a more passive ornon-polar coating surface. It is noted that deposition of the H atomsnear the coating's surface may tend to etch away any sp² or graphite C—Cbonds in that area. This increase in H near the layer's surface may alsodecrease the layer's density at this outermost layer portion.

FIG. 2 is a side cross sectional view of a coated article according toanother embodiment of this invention, including substrate 1 (e.g.glass), hydrophobic DLC inclusive coating system 5 including layer 2, 3,as described above with regard to the FIG. 1 embodiment, andintermediate layer(s) 4 provided between layer 2 and substrate 1.Intermediate layer 4 may be of or include, for example, any of siliconnitride, silicon oxide, an infrared (IR) reflecting layer or layersystem, an ultraviolet (UV) reflecting layer of layer system, anotherDLC inclusive layer(s), or any other type of desired layer(s). In thisembodiment, it is noted that coating system 5 is still “on” substrate 1.The term “on” herein means that substrate 1 supports DLC coating system5, regardless of whether or not other layer(s) (e.g. 4) are providedtherebetween. Thus, hydrophobic coating system 5 may be provideddirectly on substrate 1 as shown in FIG. 1, or may be provided onsubstrate 1 with another coating or layer 4 therebetween as shown inFIG. 4.

Exemplar coatings/layers that may be used as low-E or othercoating(s)/layer(s) 4 are shown and/or described in any of U.S. Pat.Nos. 5,837,108, 5,800,933, 5,770,321, 5,557,462, 5,514,476, 5,425,861,5,344,718, 5,376,455, 5,298,048, 5,242,560, 5,229,194, 5,188,887 and4,960,645, which are all hereby incorporated herein by reference.

In certain embodiments, coating system 5 is at least about 75%transparent to or transmissive of visible light rays, preferably atleast about 85%, and most preferably at least about 95%.

When substrate 1 is of glass, it may be from about 1.0 to 5.0 mm thick,preferably from about 2.3 to 4.8 mm thick, and most preferably fromabout 3.7 to 4.8 mm thick. In certain embodiments, another advantage ofcoating system 5 is that the ta-C therein may reduce the amount of soda(e.g., from a soda-lime-silica glass substrate 1) that can reach thesurface of the coated article and cause stains/corrosion. In suchembodiments, substrate 1 may be soda-lime-silica glass and include, on aweight basis, from about 60-80% SiO₂, from about 10-20% Na₂O, from about0-16% CaO, from about 0-10% K₂O, from about 0-10% MgO, and from about0-5% Al₂O₃. Iron and/or other additives may also be provided in theglass composition of the substrate 1. In certain other embodiments,substrate 1 may be soda lime silica glass including, on a weight basis,from about 66-75% SiO₂, from about 10-20% Na₂O, from about 5-15% CaO,from about 0-5% MgO, from about 0-5% Al₂O₃, and from about 0-5% K₂O.Most preferably, substrate 1 is soda lime silica glass including, byweight, from about 70-74% SiO₂, from about 12-16% Na₂O, from about 7-12%CaO, from about 3.5 to 4.5% MgO, from about 0 to 2.0% Al₂O₃, from about0-5% K₂O, and from about 0.08 to 0.15% iron oxide. Soda lime silicaglass according to any of the above embodiments may have a density offrom about 150 to 160 pounds per cubic foot (preferably about 156), anaverage short term bending strength of from about 6,500 to 7,500 psi(preferably about 7,000 psi), a specific heat (0-100 degrees C) of about0.20 Btu/lbF, a softening point of from about 1330 to 1345 degrees F, athermal conductivity of from about 0.52 to 0.57 Btu/hrftF, and acoefficient of linear expansion (room temperature to 350 degrees C) offrom about 4.7 to 5.0×10⁻⁶ degrees F. Also, soda lime silica float glassavailable from Guardian Industries Corp., Auburn Hills, Mich., may beused as substrate 1. Any such aforesaid glass substrate 1 may be, forexample, green, blue or grey in color when appropriate colorant(s) areprovided in the glass in certain embodiments.

In certain other embodiments of this invention, substrate 1 may be ofborosilicate glass, or of substantially transparent plastic, oralternatively of ceramic. In certain borosilicate embodiments, thesubstrate 1 may include from about 75-85% SiO₂, from about 0-5% Na₂O,from about 0 to 4% Al₂O₃, from about 0-5% K₂O, from about 8-15% B₂O₃,and from about 0-5% Li₂O.

In still further embodiments, an automotive window (e.g. windshield orside window) including any of the above glass substrates laminated to aplastic substrate may combine to make up substrate 1, with the coatingsystem(s) of any of the FIGS. 1-2 embodiments provided on the outsidesurface of such a window. In other embodiments, substrate 1 may includefirst and second glass sheets of any of the above mentioned glassmaterials laminated to one another, for use in window (e.g. automotivewindshield, residential window, commercial architectural window,automotive side window, vacuum IG window, automotive backlight or backwindow, etc.) and other similar environments.

When substrate 1 of any of the aforesaid materials is coated with atleast DLC inclusive coating system 5 according to any of the FIGS. 1-2embodiments, the resulting coated article has the followingcharacteristics in certain embodiments: visible transmittance (Ill. A)greater than about 60% (preferably greater than about 70%, and mostpreferably greater than about 80%), UV (ultraviolet) transmittance lessthan about 38%, total solar transmittance less than about 45%, and IR(infrared) transmittance less than about 35% (preferably less than about25%, and most preferably less than about 21%). Exemplary visible, “totalsolar”, UV, and IR transmittance measuring techniques are set forth inU.S. Pat. No. 5,800,933, incorporated herein by reference.

Hydrophobic performance of coating system 5 in any of the aboveembodiments is a function of contact angle θ, surface energy γ, tiltangle β, and/or wettability or adhesion energy W.

The surface energy γ of coating system 5 may be calculated by measuringits contact angle θ (contact angle θ is illustrated in FIGS. 3-4). Asessile drop 31 of a liquid such as water is placed on the coating asshown in FIG. 4. A contact angle θ between the drop 31 and underlyingcoating system 5 appears, defining an angle depending upon the interfacetension between the three phases in the point of contact. Generally, thesurface energy γ_(C) of coating system 5 can be determined by theaddition of a polar and a dispersive component, as follows:γ_(C)=γ_(CP)+γ_(CD), where γ_(CP) is the coating's polar component andγ_(CD) the coating's dispersive component. The polar component of thesurface energy represents the interactions of the surface which ismainly based on dipoles, while the dispersive component represents, forexample, van der Waals forces, based upon electronic interactions.Generally speaking, the lower the surface energy γ_(C) of coating system5, the more hydrophobic the coating and the higher the contact angle θ.

Adhesion energy (or wettability) W can be understood as an interactionbetween polar with polar, and dispersive with dispersive forces, betweencoating system 5 and a liquid thereon such as water. γ^(P) is theproduct of the polar aspects of liquid tension and coating/substratetension; while γ^(D) is the product of the dispersive forces of liquidtension and coating/substrate tension. In other words,γ^(P)=γ_(LP)*γ_(CP); and γ^(D)=γ_(LD)*γ_(CD); where γ_(LP) is the polaraspect of the liquid (e.g. water), γ_(CP) is the polar aspect of coatingsystem 5; γ_(LD) is the dispersive aspect of liquid (e.g. water), andγ_(CD) is the dispersive aspect of coating system 5. It is noted thatadhesion energy (or effective interactive energy) W, using the extendedFowkes equation, may be determined by:

W=[γ_(LP)*γ_(CP)]^(½)+[γ_(LD)*γ_(CD)]^(½)=γ_(l)(1+cosθ),

where γ_(l) is liquid tension and θ is the contact angle. W of twomaterials (e.g. coating system 5, specifically outermost or overlyinglayer 3 and water thereon) is a measure of wettability indicative of howhydrophobic the coating system is.

When analyzing the degree of hydrophobicity of outermost layer 3 of thecoating system 5 with regard to water, it is noted that for water γ_(LP)is 51 mN/m and γ_(LD) is 22 mN/m. In certain embodiments of thisinvention, the polar aspect γ_(CP) of surface energy of layer 3 is fromabout 0 to 0.2 (more preferably variable or tunable between 0 and 0.1)and the dispersive aspect γ_(CD) of the surface energy of layer 3 isfrom about 16-22 mN/m (more preferably from about 16-20 mN/m). Using theabove-listed numbers, according to certain embodiments of thisinvention, the surface energy γ_(C) of layer 3 (and thus coating system5) is less than or equal to about 20.2 mN/m, more preferably less thanor equal to about 19.5 mN/m, and most preferably less than or equal toabout 18.0 mN/m; and the adhesion energy W between water and layer 3 isless than about 25 mN/m, more preferably less than about 23 mN/m, evenmore preferably less than about 20 mN/m, and most preferably less thanabout 19 mN/m. These low values of adhesion energy W and layer 3 surfaceenergy γ_(C), and the high initial contact angles θ achievable,illustrate the improved hydrophobic nature of the coating system 5according to different embodiments of this invention. While layer 3functions to provide much of the hydrophobic nature of the coatingsystem 5, underlying DLC inclusive layer 2 improves the bondingcharacteristics of the coating system 5 to the substrate 1 (e.g., glasssubstrate) and yet still provides adequate hardness characteristicsregarding the coating system 5 as a whole.

The initial contact angle θ of a conventional glass substrate 1 withsessile water drop 31 thereon is typically from about 22-24 degrees,although it may dip as low as 17 or so degrees in some circumstances, asillustrated in FIG. 3. Thus, conventional glass substrates are notparticularly hydrophobic in nature. The provision of coating system 5 onsubstrate 1 causes the contact angle θ to increase to the anglesdiscussed herein, as shown in FIG. 4 for example, thereby improving thehydrophobic nature of the article. As discussed in Table 1 of09/303,548, the contact angle θ of a ta-C DLC layer is typically fromabout 5 to 50 degrees. However, the makeup of DLC-inclusive coatingsystem 5 described herein enables the initial contact angle θ betweenoverlying layer 3 and a water drop (i.e. sessile drop 31 of water) to beincreased in certain embodiments to at least about 80 degrees, morepreferably to at least about 100 degrees, even more preferably at leastabout 110 degrees, and most preferably at least about 125 degrees,thereby improving the hydrophobic characteristics of the DLC-inclusivecoating system. An “initial” contact angle θ means prior to exposure toenvironmental conditions such as sun, rain, abrasions, humidity, etc.

FIGS. 5-6 illustrate an exemplary linear or direct ion beam source 25which may be used to deposit layer 2 and 3 of coating system 5, clean asubstrate, or surface plasma treat a DLC inclusive coating with H and/orF according to different embodiments of this invention. Ion beam source25 includes gas/power inlet 26, anode 27, grounded cathode magnetportion 28, magnet poles 29, and insulators 30. A 3 kV DC power supplymay be used for source 25 in some embodiments. Linear source iondeposition allows for substantially uniform deposition of layer 2 and 3as to thickness and stoichiometry.

Ion beam source 25 is based upon a known gridless ion source design. Thelinear source is composed of a linear shell (which is the cathode andgrounded) inside of which lies a concentric anode (which is at apositive potential). This geometry of cathode-anode and magnetic field33 gives rise to a close drift condition. The magnetic fieldconfiguration further gives rise to an anode layer that allows thelinear ion beam source to work absent any electron emitter. The anodelayer ion source can also work in a reactive mode (e.g. with oxygen andnitrogen). The source includes a metal housing with a slit in a shape ofa race track as shown in FIGS. 5-6. The hollow housing is at groundpotential. The anode electrode is situated within the cathode body(though electrically insulated) and is positioned just below the slit.The anode can be connected to a positive potential as high was 3,000volts. Both electrodes may be water cooled in certain embodiments.Feedstock/precursor gases, described herein, are fed through the cavitybetween the anode and cathode. The gas(es) used determines the make-upof the resulting layer deposited on an adjacent substrate 1.

The linear ion source also contains a labyrinth system that distributesthe precursor gas (e.g., TMS (i.e., (CH₃)₄Si or tetramethylsilane);acetylene (i.e., C₂H₂); 3MS (i.e., trimethyldisilane); DMS (i.e.,dichloro-dimethylsilane); HMDSO (i.e., hexamethyldisiloxane); TEOS(i.e., tetraethoxysilane), etc.) fairly evenly along its length andwhich allows it to supersonically expand between the anode-cathode spaceinternally. The electrical energy then cracks the gas to produce aplasma within the source. The ions are expelled out at energies in theorder of eVc-a/2 when the voltage is Vc-a. The ion beam emanating fromthe slit is approximately uniform in the longitudinal direction and hasa Gaussian profile in the transverse direction. Exemplary ions 34 areshown in FIG. 6. A source as long as one meter may be made, althoughsources of different lengths are anticipated in different embodiments ofthis invention. Finally, electron layer 35 is shown in FIG. 6 completesthe circuit thereby enabling the ion beam source to function properly.

In alternative embodiments of this invention, an ion beam source deviceor apparatus as described and shown in FIGS. 1-3 of U.S. Pat. No.6,002,208 (hereby incorporated herein by reference in its entirety) maybe used to deposit/form DLC inclusive layer 2 and 3 on substrate 1 inaccordance with either the FIG. 1 or FIG. 2 embodiment of thisinvention. One or multiple such ion beam source devices may be used.

In certain embodiments, the same ion beam source 25 may be used todeposit both of layer 2 and 3; one after the other. In other embodimentsof this invention two separate ion beam sources may be provided, a firstfor depositing layer 2 on substrate 1 and the second for depositinglayer 3 over layer 2. In certain embodiments, another ion beam sourcemay be provided for initially cleaning the surface of substrate 1 priorto deposition of layer 2, 3.

Referring to FIG. 7, tilt angle β characteristics associated withcertain embodiments of this invention will be explained. In ahydrophobic coating, it is often desirable in certain embodiments tohave both a high contact angle θ (see FIG. 4) in combination with a lowtilt angle β. As shown in FIG. 7, tilt angle β is the angle relative tothe horizontal 43 that the coated article must be tilted before a 30 μL(volume) drop 41 (e.g., of water) thereon begins to flow down the slantat room temperature without significant trail. A low tilt angle meansthat water and/or other liquids may be easily removed from the coatedarticle upon tilting the same or even in high wind conditions. Incertain embodiments of this invention, coated articles herein (withlayer 2, 3) have an initial tilt angle β of no greater than about 30degrees, more preferably no greater than about 20 degrees, and even morepreferably no greater than about 10 degrees. In certain embodiments, thetilt angle does not significantly increase over time upon exposure tothe environment and the like, while in other embodiments it may increaseto some degree over time.

Referring to FIGS. 1-2 and 5-6, an exemplary method of depositing acoating system 5 on substrate 1 will now be described. This method isfor purposes of example only, and is not intended to be limiting.

Prior to coating system 5 being formed on glass substrate 1, the topsurface of substrate 1 is preferably cleaned by way of a first linear ordirect ion beam source. For example, a glow discharge in argon (Ar) gasor mixtures of Ar/O₂ (alternatively CF₄ plasma) may be used to removeany impurities on the substrate surface. Such interactions arephysio-chemical in nature. This cleaning creates free radicals on thesubstrate surface that subsequently can be reacted with other monomersyielding substrate surfaces with specialized properties. The power usedmay be from about 100-300 Watts. Substrate 1 may also be cleaned by, forexample, sputter cleaning the substrate prior to actual deposition ofcoating system 5; using oxygen and/or carbon atoms at an ion energy offrom about 800 to 1200 eV, most preferably about 1,000 eV.

After cleaning, the deposition process begins using a linear ion beamdeposition technique via second ion beam source as shown in FIGS. 5-6,or in FIGS. 1-3 of the '208 patent; with a conveyor having moved thecleaned substrate 1 from first source to a position under the secondsource. The second ion beam source functions to deposit a ta-C (or DLC)inclusive layer 2 on substrate 1, with at least TMS being used as theprecursor or feedstock gas fed through the source. Because of the Si inthe TMS gas used in the source, the resulting layer 2 formed onsubstrate includes Si as well as DLC. The Si portion of DLC inclusivelayer 2 enables good bonding of layer 2 to substrate 1, and thus willalso improve the bonding characteristics of layer 3 to the substrate vialayer 2.

After layer 2 has been formed, either the same or another ion beamsource is used to deposit layer 3 over (directly on in preferredembodiments) layer 2. To deposit overlying DLC inclusive layer 3,another gas such as at least C₂H₂ is fed through the source so that thesource expels the ions necessary to form layer 3 overlying layer 2 onsubstrate 1. The C₂H₂ gas may be used alone, or in exemplary alternativeembodiments the gas may be produced by bubbling a carrier gas (e.g.C₂H₂) through a precursor monomer (e.g. TMS or 3MS) held at about 70degrees C (well below the flashing point). Acetylene feedstock gas(C₂H₂) is used in certain embodiments to prevent or minimize/reducepolymerization and to obtain an appropriate energy to allow the ions topenetrate the surface on the substrate and subimplant therein, therebycausing layer 3 to intermix with layer 2 in at-least an interfaceportion between the layers. The actual gas flow may be controlled by amass flow controller (MFC) which may be heated to about 70 degrees C. Incertain optional embodiments, oxygen (O₂) gas may be independentlyflowed through an MFC. The temperature of substrate 1 may be roomtemperature; an arc power of about 1000 W may be used; precursor gasflow may be about 25 sccm; the base pressure may be about 10⁻⁶ Torr. Theoptimal ion energy window for the majority of layer 2, 3 is from about100-1,000 eV (preferably from about 100-400 eV) per carbon ion. At theseenergies, the carbon in the resulting layer 2, 3 emulates diamond, andsp³ C—C bonds form. However, compressive stresses can develop in ta-Cwhen being deposited at 100-150 eV. Such stress can reach as high as 10GPa and can potentially cause delamination from many substrates. It hasbeen found that these stresses can be controlled and decreased byincreasing the ion energy during the deposition process to a range offrom about 200-1,000 eV.

As stated above, layer 2 and 3 intermix with one another at theinterface between the two layers, thereby improving the bonding betweenthe layers. At particle energies (carbon energies) of several hundredeV, a considerable material transport can take place over several atomicdistances. This is caused by the penetration of fast ions and neutralsas well as by the recoil displacement of struck atoms. At sufficientlyhigh particle energies and impact rates, there is an enhanced diffusionof the thermally agitated atoms near the film surface that occurs viathe continuously produced vacancies. In the formation of ta-C:H, theseeffects can help improve film adhesion by broadening the interface(i.e., making it thicker, or making an interfacial layer between the twolayer 2 and 3 (or between layer 2 and glass 1) due to atom mixing).After layer 2 is deposited, the carbon from layer 3 implants into layer2 (i.e., subimplantation) so as to make the bond better of layer 3 tothe substrate. Thus, layer 2 and 3 are contiguous due to thisintermixing, and this “smearing” between the layers enhances theadhesion of layer 3 to both layer 2 and thus the substrate 1.

High stress is undesirable in the thin interfacing portion of layer 2that directly contacts the surface of a glass substrate 1 in the FIG. 1embodiment. Thus, for example, the first 1-40% thickness (preferably thefirst 1-20% and most preferably the first 5-10% thickness) of layer 2may optionally be deposited on substrate 1 using high anti-stress energylevels of from about 200-1,000 eV, preferably from about 400-500 eV.Then, after this initial interfacing layer portion of layer 2 has beengrown, the ion energy in the ion deposition process may be decreased(either quickly or gradually while deposition continues) to about100-200 eV, preferably from about 100-150 eV, to grow the remainder oflayer(s) 2 and/or layer 3. Thus, in certain embodiments, because of theadjustment in ion energy during the deposition process, DLC inclusivelayer 2, 3 may optionally have different densities and differentpercentages of sp³ C—C bonds at different layer portions thereof (thelower the ion energy, the more sp³ C—C bonds and the higher thedensity).

While direct ion beam deposition techniques are preferred in certainembodiments, other methods of deposition may also be used in differentembodiments. For example, filtered cathodic vacuum arc ion beamtechniques may be used to deposit layer 2, 3. Also, in certainembodiments, CH₄ may be used as a feedstock gas during the depositionprocess instead of or in combination with the aforesaid C₂H₂ gas.

A third or even fourth ion beam source is optional. In certainembodiments of this invention, the hydrophobicity of coating system 5can be further enhanced using a plasma treatment by another source orgrafting procedure after the main portion of DLC-inclusive coatingsystem 5 has been deposited. This technique using a another ion beamsource may remove certain polar functional groups at the outermostsurface of layer 3, thereby altering the surface chemical reactivity(i.e. lowering surface energy) while the bulk of coating system 5remains the same or substantially unaffected. In such optionalembodiments, after a conveyor has moved the DLC-coated substrate fromthe second source station to a position under this source, the plasmatreatment by this source may introduce, e.g., hydrogen (H) atoms intothe outermost surface of layer 3, thereby making the coating's surfacesubstantially non-polar and less dense than the rest of the coating.These H atoms are introduced, because H₂ and/or ArH₂ feedstock gas isused by this source in certain embodiments. Thus, third source 63 doesnot deposit any significant amounts of C atoms or Si atoms; but insteadtreats the outermost surface of the ta-C:SiO coating by adding H atomsthereto in order to improve its hydrophobic characteristics. This plasmatreatment may also function to roughen the otherwise smooth surface. Itis noted that H₂ feedstock gas is preferred in the ion beam source whenit is not desired to roughen the surface of coating system 5, while ArH₂feedstock gas is preferred in surface roughing embodiments. In otheroptional embodiments, this source may be used to implant F ions/atoms into the outermost surface of layer 3.

Coating system 5 according to different embodiments of this inventionmay have the following characteristics: coefficient of friction of fromabout 0.02 to 0.15; good abrasion resistance; an average density of fromabout 2.0 to 3.0 g/cm²; permeability barrier to gases and ions; surfaceroughness less than about 0.5 nm; inert reactivity to acids, alkalis,solvents, salts and water; corrosion resistance; variable or tunablesurface tension; tunable optical bandgap of from about 2.0 to 3.7 eV; IRtransmission @ 10 μm of at least about 85%; UV transmission @ 350 nm ofno greater than about 30%; tunable refractive index @ 550 nm [n=1.6 to2.3; k=0.0001 to 0.1], permittivity @ GHz 4.5; an undoped electricalresistivity of at least about 10¹⁰ Ω/cm; dielectric constant of about 11@ 10 kHz and 4 @ 100 MHz; an electrical breakdown strength (V cm⁻¹) ofabout 10⁶; thermal coefficient of expansion of about 9×10⁻⁶/C; andthermal conductivity of about 0.1 Wcm K.

Three examples of TMS-formed DLC inclusive anchor layer 2 are asfollows. Each such layer 2 was deposited on substrate 1 usingtetramethylsilane (TMS) and O₂ gas introduced within the linear ion beamsource apparatus of FIGS. 5-6. All samples were of approximately thesame thickness of about 750 A. A low energy electron flood gun was usedto sharpen the spectral analysis conducted by x-ray photo electronspectroscopy (XPS) for chemical analysis. In XPS analysis of a layer 2,high energy x-ray photons (monochromatic) impinge on the surface of thelayer. Electrons from the surface are ejected and their energy andnumber (count) measured. With these measurements, one can deduce theelectron binding energy. From the binding energy, one can determinethree things: elemental fingerprinting, relative quantity of elements,and the chemical state of the elements (i.e. how they are bonding).Components used in the XPS analysis include the monochromatic x-raysource, an electron energy analyzer, and electron flood gun to preventsamples from charging up, and an ion source used to clean and depthprofile. Photoelectrons are collected from the entire XPS fieldsimultaneously, and using a combination of lenses before and after theenergy analyzer are energy filtered and brought to a channel plate. Theresult is parallel imaging in real time images. Sample Nos. 1-3 of DLCinclusive layer 2 were made and analyzed using XPS, which indicated thatthe samples included the following chemical elements by atomicpercentage (H was excluded from the chart below).

Sample No. C O Si F 1 54.6% 23.7% 20.5% 1.2% 2 45.7% 21.7% 32.7%   0% 359.5% 22.7% 17.8%   0%

H was excluded from the XPS analysis because of its difficulty tomeasure. Thus, H atoms present in the coating Sample Nos. 1-3 were nottaken into consideration for these results. For example, if Sample No. 1included 9% H by atomic percentage, then the atomic percentages of eachof the above-listed elements C, O, Si and F would be reduced by anamount so that all five atomic percentages totaled 100%. As can be seen,F is optional and need not be provided. Oxygen is also optional.

While TMS is described above as a primary precursor or feedstock gasutilized in the ion beam deposition source for depositing the underlyingDLC inclusive layer 2, other gases may in addition or instead be used.For example, other gases such as the following may be used either alone,or in combination with TMS, to form layer 2: silane compounds such asTMS, diethylsilane, TEOS, dichlorodimethylsilane, trimethyldisilane,hexamethyldisiloxane, organosilane compounds; organosilazane compoundssuch as hexamethyldisilazane and tetramethyldisilazane; and/ororgano-oxysilicon compounds such as tetramethyldisiloxane,ethoxytrimethylsilane, and organo-oxysilicon compounds. Each of thesegases includes Si; and each of these gases may be used either alone toform layer 2, or in combination with one or more of the other listedgases. In certain embodiments, the precursor gas may also furtherinclude N, F and/or O in optional embodiments, for layer 2 and/or layer3.

With regard to layer 3, a hydrocarbon gas such as acetylene is preferredfor forming the layer. However, other gases such as ethane, methane,butane, cyclohexane, and/or mixtures thereof may also (or instead) beused in the ion beam source to form layer 3.

In certain embodiments of this invention, coating system 5 has a contactangle of at least about 70°, more preferably at least about 80°, andeven more preferably at least about 100° after a taber abrasionresistance test has been performed pursuant to ANSI Z26.1. The testutilizes 1,000 rubbing cycles of coating system 5, with a load aspecified in Z26.1 on the wheel(s). Another purpose of this abrasionresistance test is to determine whether the coated article is resistiveto abrasion (e.g. whether hazing is less than 4% afterwards). ANSI Z26.1is hereby incorporated into this application by reference.

FIGS. 8-9 illustrate the makeup of a coating system 5 including layer 2and 3 according to an embodiment of this invention. X-ray PhotoelectronSpectroscopy (XPS)/Electron Spectroscopy for Chemical Analysis (ESCA)was used to develop these graphs from the sample product. This is usedto characterize inorganic and organic solid materials. In order toperform such measurements on a sample product as was done with regard toFIGS. 8-9, the surface of the coating system was excited with Almonochromatic x-rays (1486.6 eV) and the photoelectrons ejected from thesurface were energy analyzed. Low resolution analysis, i.e., a surveyscan, can be used to identify elements (note that H, He, and F were notincluded in the analysis of FIGS. 8-9 even though at least H and/or Fwere present in the coating system 5) and establish the illustratedconcentration table in units of atomic percentage (%). Detection limitswere from about 0.1 to 0.05 atom %. High resolution analysis ofindividual photoelectron signals, i.e., C 1s, can be used to identifychemical bonding and/or oxidation state. Information on the surface isobtained from a lateral dimension as large as 1 mm diameter and from adepth of 0-10 μm. To acquire information from slightly greater depths,angle resolved measurements can be made.

Referring more particularly to FIG. 8, that figure illustrates themakeup with regard to C, O and Si throughout the thickness of coatingsystem 5 in the FIG. 1 embodiment, including both of layer 2 and 3.Cycle number 1 is at the surface of the coating system 5 where layer 3meets the surrounding atmosphere, while cycle number 19 is believed tobe within the underlying glass substrate 1. Thus, it is believed thatthe interface between glass substrate 1 and underlying DLC inclusivelayer 2 is at about cycle number 15 where the C % begins tosignificantly decrease. The “time” and “depth” columns refers to depthinto coating system 5 from the exterior surface thereof as compared tothe depth into a conventional SiO₂ that would be achieved over the sametime period. Thus, the angstrom depth illustrated in FIG. 8 is not theactual depth into coating system 5, but instead is how deep into a SiO₂layer the sputtering would reach over the corresponding time.

In FIG. 8, cycle number 1 may be affected from contamination of theouter surface of the coating system 5 and may be disregarded in effect.At least cycle numbers 2-6 refer or correspond to overlying DLCinclusive layer 3 as evidenced by the high carbon amounts (i.e., greaterthan 94% C in layer 3 according to FIG. 8). Meanwhile, at least cyclenumbers 9-13 refer or correspond to underlying DLC inclusive layer 2, asevidence by the lower C amounts shown in FIG. 8. Thus, it can be seenthat layer 2 includes less C than layer 3, and is therefor less denseand less hard. Moreover, it can be seen that layer 2 includes more Sithan layer 3 (and optionally more oxygen (O)). Cycle numbers 7-8 referor correspond to the interface or intermixing layer portion betweenlayer 2 and 3; as the coating system 5 at these thickness portionsincludes C and Si amounts between the amounts in respective layer 2 and3. Thus, these cycle numbers 7-8 illustrate the intermixing (i.e.,subimplantation of atoms from layer 3 in layer 2) or smearing betweenlayer 2, 3 discussed herein. Meanwhile, cycle numbers 14-15 refer orcorrespond to the interfacial layer between layer 2 and the glasssubstrate 1, while cycle numbers 16-19 refer or correspond to the glassitself with its high SiO₂ content.

Still referring to FIG. 8, it can be seen that layer 2 (cycles 9-13)includes more Si than layer 3. Moreover, it can be seen that portions oflayer 2 (cycles 9-13) generally include at least about twice as much Cas Si; while portions of layer 3 (cycles 2-6) generally include at leastabout ten (10) times as much C as Si, more preferably at least abouttwenty (20) times as much C as Si (from an atomic perspective).Additionally, it can be seen that select cross sections of layer 2include at least about five (5) times as much Si as select crosssections of layer 3, more preferably at least about seven (7) times asmuch, and most preferably at least about eight (8) times as much.Elements such as H and F, one or both of which are in layer 2 and/or 3,are not shown in the FIG. 8 analysis. Finally, it can be seen in FIG. 8(and in FIG. 9) that throughout a substantial portion of coating system5 (i.e., at least about half of the thickness of the DLC portion of thecoating system) the amount of C progressively increases through thethickness toward the exterior surface of the coating system, while theamount of Si progressively decreases through the thickness toward theexterior surface of the coating system. Optionally, the amount of oxygen(O) may also progressively decrease through the thickness toward theexterior surface of the coating system as shown in FIGS. 8-9.

FIG. 9 is a depth (relative to SiO₂) versus atomic concentration graphillustrating the respective amounts of C, O and Si atoms in the coatingsystem 5 sample analyzed in FIG. 8. It is noted that these threematerials were the only types analyzed in these two Figures so that theatomic concentration percentage is relative to only these three types ofatoms. As can be seen in FIG. 9, the C percentage is higher the closerto the exterior surface of layer 3 one gets which is indicative of thegreater hardness and density of layer 3 relative to layer 2. Moreover,it can be seen that the Si atom percentage increases the deeper one goesinto the coating system 5 illustrating that layer 2 has more Si atomsthan layer 3 at certain cross sectional thickness thereof. It can alsobe seen that the number of O atoms increases the deeper into the coatingsystem one goes.

While the embodiments described above illustrate only two DLC inclusivelayer 2 and 3, it will be understood by those skilled in the art thatadditional DLC inclusive layers may be provided in other embodiments ofthis invention. Such additional DLC inclusive layer(s) may be locatedunder layer 2, or between layer 2 and 3. In still further embodiments ofthis invention, other types of layer(s) may be provided between layer 2and 3.

As will be appreciated by those skilled in the art, coated articlesaccording to different embodiments of this invention may be utilized inthe context of automotive windshields, automotive side windows,automotive backlites (i.e., rear windows), architectural windows,residential windows, ceramic tiles, shower doors, and the like.

Once given the above disclosure, many other features, modifications, andimprovements will become apparent to the skilled artisan. Such otherfeatures, modifications, and improvements are, therefore, considered tobe a part of this invention, the scope of which is to be determined bythe following claims.

What is claimed is:
 1. A coated glass article comprising: a glasssubstrate comprising, on a weight basis: SiO₂ from about 60-80%, Na₂Ofrom about 10-20%, CaO from about 0-16%, K₂O from about 0-10%, MgO fromabout 0-10%, Al₂O₃ from about 0-5%; a hydrophobic coating systemincluding diamond-like carbon (DLC) and sp³ carbon-carbon bonds providedon said glass substrate; said hydrophobic coating system including firstand second DLC inclusive layers, said first layer including silicon (Si)and being provided between said second layer and said substrate; whereinsaid second layer is deposited in a manner so that said second layer hasa higher hardness and higher density than said first layer; and whereinsaid hydrophobic coating system has an initial contact angle θ with asessile drop of water thereon of at least about 80 degrees, and anaverage hardness of at least about 10 GPa.
 2. The coated glass articleof claim 1, wherein said initial contact angle is at least about 100degrees.
 3. The coated glass article of claim 2, wherein said initialcontact angle is at least about 110 degrees.
 4. The coated glass articleof claim 2, wherein said initial contact angle is at least about 125degrees.
 5. The coated glass article of claim 1, wherein said coatingsystem has a surface energy γ_(C) of less than or equal to about 20.2mN/m.
 6. The coated glass article of claim 1, wherein said coatingsystem has a surface energy γ_(C) of less than or equal to about 19.5mN/m.
 7. The coated glass article of claim 1, wherein said coatingsystem has a surface energy γ_(C) of less than or equal to about 18.0mN/m, and wherein a refractive index “n” of said first layer is fromabout 1.5 to 1.7.
 8. The coated glass article of claim 1, wherein saidfirst layer is in direct contact with said glass substrate.
 9. Thecoated glass article of claim 1, further comprising an intermediatelayer disposed between said coating system and said glass substrate. 10.The coated glass article of claim 1, further comprising a low-E orIR-reflective layer system disposed between said coating system and saidglass substrate.
 11. The coated glass article of claim 1, wherein saidglass substrate is a soda lime silica glass substrate including fromabout 66-75% SiO₂, from about 10-20% Na₂O, from about 5-15% CaO, fromabout 0-5% MgO, from about 0-5% Al₂O₃, and from about 0-5% K₂O.
 12. Thecoated glass article of claim 1, wherein said hydrophobic coating systemhas an average hardness of at least about 20 GPa.
 13. The coated glassarticle of claim 1, wherein said first layer is deposited using a firstgas including silicon (Si) in an ion beam source and said second layeris deposited using a second gas different than said first gas.
 14. Thecoated glass of claim 1, wherein each of said first and second layerscomprises silicon (Si), and wherein said first layer comprises moresilicon (Si) than said second layer.
 15. The coated glass article ofclaim 1, wherein the coated glass article comprises the followingcharacteristics: visible transmittance (Ill. A): >60% UV transmittance:<38% IR transmittance: <35%.
 16. The coated glass article of claim 1,wherein each of said first and second layers include sp³ carbon-carbonbonds.
 17. The coated glass article of claim 1, wherein at least about50% of carbon-carbon bonds in said second layer are sp³ carbon-carbonbonds.
 18. A coated article comprising: a substrate; a coating systemincluding first and second diamond-like carbon (DLC) inclusive layersprovided on said substrate, said first layer further including silicon(Si); and wherein said coating system has an initial contact angle θwith a drop of water of at least about 80 degrees, and an averagehardness of at least about 10 GPa.
 19. The coated article of claim 18,wherein said initial contact angle is at least about 100 degrees, andwherein said first layer includes more Si than said second layer, andsaid first layer is located at least partially between said substrateand said second layer.
 20. The coated article of claim 18, wherein saidsubstrate comprises at least one of glass, ceramic, and plastic; andwherein a cross sectional thickness of said first layer includes atleast about five (5) times as many silicon (Si) atoms as a crosssectional thickness of said second layer.
 21. The coated article ofclaim 18, wherein said coating system is one of: (i) in direct contactwith said substrate, and (ii) on said glass substrate in a manner suchthat at least one intermediate layer is disposed between said substrateand said coating system.
 22. The coated article of claim 18, whereinsaid coating system has an average hardness of from about 20-80 GPa. 23.The coated article of claim 18, wherein the substrate is glass and thecoated article comprises the following characteristics: visibletransmittance (Ill. A): >60% UV transmittance: <38% IR transmittance:<35%.
 24. The coated article of claim 18, wherein at least about 50% ofcarbon-carbon bonds in said second layer are sp³ carbon-carbon bonds,and wherein said first layer also comprises sp³ carbon-carbon bonds. 25.The coated article of claim 18, wherein an outermost 10 angstrom layerportion of said second layer includes in atomic percentage: from about5-60% carbon (C), from about 0-40% oxygen (O), from about 0-40% silicon(Si), from about 10-95% hydrogen (H), and from about 0-10% fluorine (F).26. A coated article comprising: a substrate; a coating system includingat least one diamond-like carbon (DLC) inclusive layer provided on saidsubstrate; and wherein said coating system has an initial contact angleθ with a drop of water of at least about 80 degrees, an initial tiltangle β of no greater than about 30 degrees, and an average hardness ofat least about 10 GPa.
 27. The coated article of claim 26, wherein saidcoating system has an initial contact angle θ with a drop of water of atleast about 100 degrees, and an initial tilt angle β of no greater thanabout 20 degrees.
 28. The coated article of claim 27, wherein saidcoating system has an initial tilt angle β of no greater than about 10degrees.
 29. The coated article of claim 26, wherein said coating systemincludes first and second diamond-like carbon inclusive layers depositedusing different gases, respectively, so that said first layer includesmore Si than said second layer; wherein said first layer is locatedbetween said second layer and said substrate; and wherein said secondlayer has a greater hardness and a greater density than said firstlayer.
 30. The coated article of claim 26, wherein said coating systemincludes first and second DLC inclusive layers; and wherein a crosssection of said first DLC inclusive layer includes at least about five(5) times as much Si as a cross sectional thickness of said second DLCinclusive layer.
 31. The coated article of claim 30, wherein a crosssectional thickness of said first layer includes at least about two (2)times as many O atoms as a cross sectional thickness of said secondlayer.
 32. The coated article of claim 31, wherein a cross sectionalthickness of said first layer includes substantially less C atoms than across sectional thickness of said second layer.
 33. A coated articlecomprising: a substrate; a coating system including a diamond-likecarbon (DLC) inclusive portion having at least one layer provided onsaid substrate; and wherein an amount of carbon, C, progressivelyincreases through a substantial portion of a thickness of the DLCinclusive portion toward an exterior surface of the coating system. 34.The article of claim 33, wherein an amount of Si progressively decreasesthrough the substantial portion of the thickness of the DLC inclusiveportion toward the exterior surface of the coating system.
 35. Thearticle of claim 33, wherein an amount of oxygen (O) progressivelydecreases through the substantial portion of the thickness of the DLCinclusive portion toward the exterior surface of the coating system. 36.The article of claim 33, wherein said coating system has an initialcontact angle θ with a drop of water of at least about 80 degrees, andan average hardness of at least about 10 GPa.